Dispensing micropipette apparatus having disposable parts

ABSTRACT

This invention is a dispensing micropipette apparatus having disposable parts, which apparatus includes a capillary tube into which fluid is drawn in the desired amount by a wire plunger. The upper end of the wire plunger is releasably secured by spring means to a holder which includes a finger loop for operating the wire plunger axially within the capillary tube, for drawing fluid into, and dispensing fluid from, the apparatus in a one-handed operation. The tube and plunger contaminated by the fluid may then be dropped from the holder by operation of the spring means.

United States Patent; 11 1 Druminond et al.-

1 11 3,720,354 1 1March 13, 1973 DISPENSING MICROPIPETTE APPARATUSHAVING DISPOSABLE PARTS [75] Inventors: Michael E. Drummond, WestChester; John E. Robinson, Springfield, both ofPa,

[73] Assignee: Drummond Instrument Company,

v Broomall, Pa. 22 Filed Sept. 24, 1970 211 Appl.No.: 75,203

1521' user ..222/386 51] Int.Cl ..c01r11/0o 58 Field ofSearch..141/2s-27;

[56] References Cited UNITED STATES PATENTS Johnson ..l28/218 C XDrummond et a1. "128/218 C X 9/1968 Harris ..128/2l8 C 3,525,264 8/1970Nieglos et a1. ..73/425.6 1,156,240 10/1915 McKay ...73/425.6 X2,863,319 12/1958 McLin ..73/425.4 P

Primary Examiner-Robert B. Reeves Assistant ExaminerJohn P. ShannonAtt0rneyShlesin'ger, Arkwright & Garvey [57] ABSTRACT This invention isa dispensing micropipette apparatus having disposable parts, whichapparatus includes a capillary tube into which fluid is drawn in thedesired amount by a wire plunger. The upper end of the wire plunger isreleasably secured by spring means to a holder which includes a fingerloop for operating the wire 'plunger axially withinthe capillary tube,for drawing fluid into, and dispensing fluid from, the apparatus in aone-handed operation. The tube and plunger contaminated by the fluid maythen be dropped from the holder by operation of the spring means.

10 Claims, 7 Drawing Figures PATENTEDMAR 1 3197s SHEET 1 or 2 INVENTORSMICHAEL E. DRUMMOND JOHN E. ROBINSON si/ w mg FIG! fl ATTORNEYSPATENTEUHARIBISYS 3,720,354

' SHEET 2 0r 2 42 FIG. 5

INVENTORS MICHAEL E. DRUMMOND JOHN E. ROBlNSON ATTORNEYS DISPENSINGMICROPIPETTE APPARATUS HAVING DISPOSABLE PARTS OBJECTS OF THE INVENTIONA further object is to provide a dispensing micropipette apparatuswherein the wire plunger is releasably held in the holder by a springmember, the spring member being operated to release the plunger andmicropipette from the holder for disposal after use, or in the event themicropipette becomes broken, release being effected without touching theplunger or micropipette, thereby preventing contaminating the user withthe fluid drawn into the micropipette.

A still further object is to provide a dispensing micropipette apparatusemploying a minimum of simple, low-cost parts, which are readilyassembled for use.

Other objects will be apparent from the following description of thepresently preferred form of the present invention taken in connectionwith the appended drawings.

DESCRIPTION OF FIGURES OF DRAWINGS FIG. l is an enlarged fragmentaryperspective view of the dispensing micropipette apparatus of the presentinvention, illustrating its use;

FIG. 2 is a fragmentary side elevational view of the same;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2, lookingin the direction of the arrows;

FIG. 4 is a fragmentary perspective view of the spring member and wireplunger forming a part of the present invention, illustrating theirmanner of interengagement;

FIG. 5 is an enlarged longitudinal sectional view of a wire plunger andcapillary tube forming a part of the present invention;

- FIG. 6 is a perspective view illustrating the manner of release of thewire plunger and capillary tube from the holder after use, and

FIG. 7 is an enlarged sectional view similar to FIG. 5, illustrating amodified form of the invention for use with a different sized capillarytube.

DESCRIPTION OF FIGS. 1 TO 6 The apparatus of the present inventiongenerally includes a holder unit ll] to which is attached filling anddispensing unit 112.

As shown to advantage in FIGS. 1 to 3, holder unit 10 includes agenerally rectangular body 14, one end of which issues into afinger-engaging loop 16. Body 14 is provided with a central longitudinalbore 18 which communicates with a cut-out section 20.

A substantially Z-shaped spring member generally designated 22 issecured to body 14 by a screw 24. As shown to advantage in FIG. 4,Z-shaped member 22 includes a substantially flat portion 26, a part ofwhich is held in contiguous relationship with body portion 14 by a screw24. A central part of portion 26 is provided with an opening 28 to lendgreater resiliency to the spring.

A terminal of portion 26 issues into an angular or sloping portion 30which extends through cut-out section 20 of of body 14 at approximatelya 45 angle to portion 26. Angular portion 30 is provided with a circularopening 32 which is in alignment with longitudinal bore 18 of body 14.

The free terminal of angular portion 30 then issues into a flat springplate 34 which lies in spaced, substantially parallel relationship toholder unit 10 and to flat portion 26.

Filling and dispensing unit 12 includes a precision capillary tube 36having one or more graduations 38 marked thereon. A wire plunger 40 ispositioned within capillary tube 36 for longitudinal movement withrespect thereto, for the purpose of admitting fluid to, and dispensingfluid from, capillary tube 36. In the form of invention illustrated inFIGS. 1 to 5, wire plunger 40 is of smaller diameter than the internaldiameter of capillary tube 36. Therefore, one terminal of wire plunger40 is provided with a coating 42 of Teflon or other suitable material,the outer periphery of which engages the internal wall of capillary tube36, to effect drawing of fluid into, and dispensing liquid from, tube36.

Adjacent the opposite terminal of wire plunger 40 is a peripheralannular recess 44 which, upon insertion of wire plunger 40 throughlongitudinal bore 18 of body 14, is engaged by that portion of member 30forming circular opening 32, for holding the wire plunger in the boreunder urging of Z-shaped spring member 22.

OPERATION In use of the apparatus of the present invention, thedispensing unit thereof is grasped by four fingers of the hand, with theindex finger extending through loop 16 of holder unit 10 as shown inFIG. 1. By movement of the index finger, wire plunger 40 may be movedlongitudinally through capillary tube 36 to draw fluid into the tube.The amount of fluid drawn into the tube may be accurately controlled bymovement of the index finger. I

The fluid may then be dispensed from the tube by movement of the indexfinger held within the loop, in the opposite direction. Here again,precise amounts of fluid may be dispensed from the capillary tube byvirtue of the controlled movement of the wire plunger with one finger. 4

It is a salient feature of the present invention that after the tube andplunger have been contaminated by the fluid, these parts may be easilyremoved from holder unit 10 for disposal in a single-handed operation inthe manner illustrated in FIG. 6. In carrying out this operation, flatspring plate 34 is engaged by the thumb to disengage the spring from thewire plunger 40, thereby permitting the latter to gravitate from itsposition within holder unit 10, for disposal. This same procedure isalso followed in the event that the capillary tube becomes broken duringuse.

FORM OF THE INVENTION ILLUSTRATED IN FIG. 7

In FIG. 7, there has been illustrated a modified form of apparatuswherein a capillary tube 46 of smaller capacity is employed. In thisform of the invention, wire plunger 48 is passed through capillary tube46, the wire plunger being of substantially the same diameter as thediameter of the bore of capillary tube 46. Therefore, no tip member isrequired at the end of wire plunger 48, and fluid is drawn into anddispensed from, capillary tube 46 simply by longitudinal movement of thewire plunger with respect to the capillary tube.

While there has been herein shown and described the presently preferredforms of the present invention, it is to be understood that such hasbeen done for purposes of illustration only, and that various changesmay be made therein within the scope of the claims hereto appended.

What we claim is:

l. A dispensing micropipette apparatus including a. an elongated tubularmember,

b. a plunger member extending longitudinally through said tubularmember,

. at least a portion of said plunger member being of substantially thesame cross-sectional area as the internal cross-sectional area of saidelongated tubular member, whereby fluid may be drawn into, and dispensedfrom, said tubular member, by movement of said plunger member throughsaid tubular member, and

. a holder engageable with one end of said plunger member,

. said holder including a body portion having a central cut out section,

f. said holder further being provided with a longitudinal bore incommunication with said out out section, through which bore and cut outsection said plunger member is pushed,

a substantially Z-shaped spring fixed at one end to said body portion,

h. an intermediate part of said Z-shaped spring extending through thecut-out portion of said body portion,

. the intermediate part of said Z-shaped spring being provided with anopening through which an end of said plunger member passes,

j. whereby a portion of said Z-shaped spring defining the openingengages the plunger member for frictionally holding the latter in saidholder,

said holder further including finger-engaging means for facilitatingmovement of said plunger member through said tubular member.

2. The dispensing micropipette apparatus of claim 1, wherein a. saidfinger-engaging means comprises a loop through which a finger passes toeffect one-handed operation of the apparatus.

3. The dispensing micropipette apparatus of claim 2,

wherein a. said plunger member is provided with an annular recessadjacent one end thereof,

b. the annular recess being engaged by that portion of the intermediatepart of said Z-shaped spring defining the opening to preclude accidentallongitudinal movement of said plunger member with respect to saidholder.

4. The apparatus of claim 3, wherein said plunger member is providedwith a tip of substantially the same cross-sectional area as theinternal cross-sectional area of said elongated tubular member.

. The apparatus of claim 3, wherein the cross-sectional area of saidplunger member throughout its length is the same as the internalcross-sectional area of said elongated tubular member.

. A dispensing micropipette apparatus including:

. an elongated tubular member,

a plunger member extending longitudinally through said tubular member,

. at least a portion of said plunger member being of substantially thesame cross-sectional area as the internal cross-sectional area of saidelongated tubular member, whereby fluid may be drawn into, and dispensedfrom, said tubular member, by movement of said plunger memberlongitudinally through said tubular member,

. a holder engageable with one end of said plunger member,

. said holder being provided with finger engaging means for facilitatingmovement of said plunger member through said tubular member,

f. said holder including a body portion provided with a bore for thereception of said plunger member, and

. spring means carried by said holder and engageable with said plungermember for retaining the latter in said holder.

. A dispensing micropipette apparatus including:

. an elongated tubular member,

a plunger member extending longitudinally through said tubular member,

. at least a portion of said plunger member being of substantially thesame cross-sectional area as the internal cross-sectional area of saidelongated tubular member and in frictional engagement therewith, wherebyfluid may be drawn into and dispensed from said tubular member,

. a holder engageable with one end of said plunger member,

. said holder being provided with finger engaging means for facilitatingmovement of said plunger member through said tubular member,

f. means carried by said holder for normally gripping said plungermember, and

means engageable with said means gripping said plunger member forreleasing said plunger member and the tubular member in frictionalengagement therewith, for disposal.

8. The dispensing micropipette apparatus of claim 7,

wherein:

a. said finger-engaging means comprises a loop through which a fingerpasses to effect one-handed operation of the apparatus.

9. The dispensing micropipette apparatus of claim 7,

wherein:

a. said plunger member is provided with a tip of substantially the samecross-sectional area as the internal cross-sectional area of saidelongated tubular member for frictionally engaging the walls of thelatter to effect the drawing of fluid into, and dispensing fluid fromsaid tubular member.

10. The dispensing apparatus of claim 7, wherein:

a.- the cross-sectional area of said plunger member throughout itslength is the same as the internal cross-sectional area of saidelongated tubular member.

1. A dispensing micropipette apparatus including a. an elongated tubularmember, b. a plunger member extending longitudinally through saidtubular member, c. at least a portion of said plunger member being ofsubstantially the same cross-sectional area as the internalcross-sectional area of said elongated tubular member, whereby fluid maybe drawn into, and dispensed from, said tubular member, by movement ofsaid plunger member through said tubular member, and d. a holderengageable with one end of said plunger member, e. said holder includinga body portion having a central cut out section, f. said holder furtherbeing provided with a longitudinal bore in communication with said cutout section, through which bore and cut out section said plunger memberis pushed, g. a substantially Z-shaped spring fixed at one end to saidbody portion, h. an intermediate part of said Z-shaped spring extendingthrough the cut-out portion of said body portion, i. the intermediatepart of said Z-shaped spring being provided with an opening throughwhich an end of said plunger member passes, j. whereby a portion of saidZ-shaped spring defining the opening engages the plunger member forfrictionally holding the latter in said holder, k. said holder furtherincluding finger-engaging means for facilitating movement of saidplunger member through said tubular member.
 1. A dispensing micropipetteapparatus including a. an elongated tubular member, b. a plunger memberextending longitudinally through said tubular member, c. at least aportion of said plunger member being of substantially the samecross-sectional area as the internal cross-sectional area of saidelongated tubular member, whereby fluid may be drawn into, and dispensedfrom, said tubular member, by movement of said plunger member throughsaid tubular member, and d. a holder engageable with one end of saidplunger member, e. said holder including a body portion having a centralcut out section, f. said holder further being provided with alongitudinal bore in communication with said cut out section, throughwhich bore and cut out section said plunger member is pushed, g. asubstantially Z-shaped spring fixed at one end to said body portion, h.an intermediate part of said Z-shaped spring extending through thecut-out portion of said body portion, i. the intermediate part of saidZ-shaped spring being provided with an opening through which an end ofsaid plunger member passes, j. whereby a portion of said Z-shaped springdefining the opening engages the plunger member for frictionally holdingthe latter in said holder, k. said holder further includingfinger-engaging means for facilitating movement of said plunger memberthrough said tubular member.
 2. The dispensing micropipette apparatus ofclaim 1, wherein a. said finger-engaging means comprises a loop throughwhich a finger passes to effect one-handed operation of the apparatus.3. The dispensing micropipette apparatus of claim 2, wherein a. saidplunger member is provided with an annular recess adjacent one endthereof, b. the annular recess being engaged by that portion of theintermediate part of said Z-shaped spring defining the opening topreclude accidental longitudinal movement of said plunger member withrespect to said holder.
 4. The apparatus of claim 3, wherein a. saidplunger member is provided with a tip of substantially the samecross-sectional area as the internal cross-sectional area of saidelongated tubular member.
 5. The apparatus of claim 3, wherein a. thecross-sectional area of said plunger member throughout its length is thesame as the internal cross-sectional area of said elongated tubularmember.
 6. A dispensing micropipette apparatus including: a. anelongated tubular member, b. a plunger member extending longitudinallythrough said tubular member, c. at least a portion of said plungermember being of substantially the same cross-sectional area as theinternal cross-sectional area of said elongated tubular member, wherebyfluid may be drawn into, and dispensed from, said tubular member, bymovement of said plunger member longitudinally through said tubularmember, d. a holder engageable with one end of said plunger member, e.said holder being provided with finger engaging means for facilitatingmovement of said plunger member through said tubular member, f. saidholder including a body portion provided with a bore for the receptionof said plunger member, and g. spring means carried by said holder andengageable with said plunger member for retaining the latter in saidholder.
 7. A dispensing micropipette apparatus including: a. anelongated tubular member, b. a plunger member extending longitudinallythrough said tubular member, c. at least a portion of said plungermember being of substantially the same cross-sectional area as theinternal cross-sectional area of said elongated tubular member and infrictional engagement therewith, whereby fluid may be drawn into anddispensed from said Tubular member, d. a holder engageable with one endof said plunger member, e. said holder being provided with fingerengaging means for facilitating movement of said plunger member throughsaid tubular member, f. means carried by said holder for normallygripping said plunger member, and g. means engageable with said meansgripping said plunger member for releasing said plunger member and thetubular member in frictional engagement therewith, for disposal.
 8. Thedispensing micropipette apparatus of claim 7, wherein: a. saidfinger-engaging means comprises a loop through which a finger passes toeffect one-handed operation of the apparatus.
 9. The dispensingmicropipette apparatus of claim 7, wherein: a. said plunger member isprovided with a tip of substantially the same cross-sectional area asthe internal cross-sectional area of said elongated tubular member forfrictionally engaging the walls of the latter to effect the drawing offluid into, and dispensing fluid from said tubular member.